Fuel pump bellows construction

ABSTRACT

A one-piece pump bellows of a flexible, resilient material with a corrugated generally cylindrical sidewall having a plurality of interleaved outer and inner bends with interconnecting wall portions. The corrugated wall is not of uniform thickness and the thickness at the bends of the wall is greater than the maximum thickness of the interconnecting wall portions. The thickness of the interconnecting wall portions immediately adjacent the bends is less than the maximum thickness of the interconnecting wall portions. The outer bends have associated pairs of opposed circumferential ribs on the inside surface of the interconnecting walls and the inner bends have associated pairs of opposed circumferential ribs on the outside surface of the interconnecting walls. The pairs of opposed ribs are adapted to abut when the bellows is foreshortened by overstroking which decreases the maximum stress to which the bends are subjected and substantially increases the service life of the bellows.

United States Patent OConnor [54] FUEL PUMP BELLOWS CONSTRUCTION [72] Inventor: Alton J. OConnor, Cass City, Mich.

[73] Assignee: Walbro Corporation, Cass City,

Mich.

22 Filed: July 30,1971

21] Appl.No.: 167,651

521 u.s.c|. ..4l7/326,92/93,222/212, 17/412 51 Int.Cl ..F04b35/00,F0lb19/00,B65d37/00 [58] Field of Search ..92/34, 48, 93, 132; 222/183,

[56] References Cited UNITED STATES PATENTS 3,130,333 4/1964 Freye ..417/412 3,235,135 2/1966 Robert et a1 ..222/386.5 3,506,163 4/1970 Rauh et al. ..264/296 3,201,111 8/1965 Afton ..92/93 3,319,532 5/1967 Pridham ..92/34 [451 Nov. 21, 1972 Primary Examiner-William L. Freeh Assistant Examiner-G. P. La Pointe AttorneyBarnes, Kisselle, Raisch & Choate [57] ABSTRACT A one-piece pump bellows of a flexible, resilient material with a corrugated generally cylindrical sidewall having a plurality of interleaved outer and v inner bends with interconnecting wall portions. The

corrugated wall is not of uniform thickness and the thickness at the bends of the wall is greater than the maximum thickness of the interconnecting wall portions. The thickness of the interconnecting wall portions immediately adjacent the bends is less than the maximum thickness of the interconnecting wall portions. The outer bends have associated pairs of op posed circumferential ribs on the inside surface of the interconnecting walls and the inner bends have associated pairs of opposed circumferential ribs on the outside surface of the interconnecting walls. The pairs of opposed ribs are adapted to abut when the bellows is foreshortened by overstroking which decreases the maximum stress to which the bends are subjected and substantially increases the service life of the bellows.

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ATTORNEYS FUEL PUMP BELLOWS CONSTRUCTION This invention relates to fuel pumps for vehicle engines and the like and more particularly to a bellows therefore.

Objects of this invention are to provide a fuel pump bellows which has a substantially longer service life, requires less actuating force, is operable at lower environmental temperatures, and is more readily moulded than prior art fuel pump bellows.

These and other objects, features, and advantages of this invention will be apparent from the following description, appended claims, and accompanying drawings in which:

FIG. 1 is a sectional view of a fuel pump with a bellows embodying this invention.

FIG. 2 is a plan view of the bellows of FIG. 1.

FIG. 3 is an enlarged sectional view of the bellows of FIG. 1.

FIG. 4 is an enlarged fragmentary sectional view of the encircled portion of the corrugated sidewall of the bellows of FIG. 3.

REFERRING TO THE DRAWINGS FIG. 1 shows a fuel pump with a bellows 12 embodying this invention, communicating with a pump chamber 14. Fuel pump 10 has inlet and outlet passageways l6 and 18 communicating with chamber 14 through one-way intake and discharge valve assemblies 20 and 22. Bellows 12 is actuated by a solenoid as sembly 24 with a wound wire energizing coil 26 and cylindrical armature slug 28. Bellows 12 is connected to armature 28 by a nut 30 threadily engaging one end of a rod 32 extending axially through and fixed to armature 28. Bellows 12 and armature 28 are yieldably biased in one direction by a coil spring 34 bearing on a cup 36 which is also connected to the armature by nut 30. The energizing and de-energizing of coil 26 to reciprocate armature 28 and hence bellows 1 2 is controlled by an assembly of electrical contacts 38 mounted on the lower end of coil 26 with one of the contacts connected to the lower end of shaft 32 for opening and closing the contacts by the reciprocating movement of armature 28. Electrical energy is supplied to coil 26 through a binding post 40 and electrical contacts 38. The structure and operation of fuel pump 10 is explained in greater detail in US. Pat. No. 3,130,333, issued to J. R. Freye on Apr. 21, 1964, and incorporated herein by reference.

As shown in FIGS. 2 and 3, bellows 12 has axially spaced concentric upper and lower mounting rings 42 and 44 with a homogeneously integral corrugated cylindrical sidewall 46 therebetween. Lower mounting ring 44 has an annular rib 48 on its inner face adapted for sealing engagement with rod 32 of armature 28. Corrugated sidewall 46 has a plurality of interleaved outer and inner bends 50 and 52 with interconnecting generally frusto-conical wall portions S4..The entire bellows 12 is a one-piece homogeneously integral device of a resilient flexible nonmetallic synthetic rubber-like material such as the polyurethane material sold under the trademark Genthane by General Tire and Rubber Company, 1 General Street, Akron, Ohio. As shown in FIG. 4, the thickness of corrugated sidewall 50 is not uniform and the thickness of the wall at outer and inner bends 50 and 52 is greater than the maximum thickness of interconnecting portions 54 of the corrugated wall. Each outer bend 50 has an associated inwardly opening circumferential groove 56 with a pair of opposed circumferential ribs 58 on the inner surface of the interconnecting wall portions 54 adjacent the bend 50. Similarly, each inner bend 52 has an associated outwardly opening groove 60 with a pair of opposed circumferential ribs 62 on the outer surface of the wall portions 54 adjacent the bend 52. The minimum thickness of wall portions 54 immediately ad jacent the apex of grooves 56 and 60 is less than the maximum thickness of the wall portions 54.

In use, bellows 12 is installed in fuel pump 10 which is connected to a source of direct current through terminal post 40 to energize solenoid 24 and reciprocate bellows 12. The bias of spring 34 of pump 10 foreshortens bellows 12 from its free length and shifts armature 28 generally axially upwardly (as shown in FIG. 1) to close the contacts of switch 38. Closure of the contacts of switch 38 energizes coil 26 to move armature 28 axially downward against the bias of spring 34 which then extends bellows l2 beyond its free length and opens the contacts of switch assembly 38. Opening of the contacts de-energizes coil 26 allowing spring 34 to move armature 28 axially upward which foreshortens bellows 12 from its free length and again closes the contacts of switch assembly 38, to thus repetively reciprocate bellows 12. This reciprocation of bellows 12 provides the pumping action which moves the fluid from inlet 16 through chamber 14 and discharges the fluid through outlet 18. The length of the reciprocal motion imparted to bellows 12 and switch assembly 24 is dependent on the pressure of the fluid in chamber 14 and whether it is in liquid or gaseous form. When the fluid in chamber 14 is in gaseous form, solenoid assembly 24 imparts a longer stroke or length of reciprocating motion to bellows 12 than when a liquid is in chamber 14 due to the incompressability of the liquid and the greater energy required to move the liquid through chamber 14. Normally the fluid in chamber 14 is in the form of liquid fuel, but it can become gaseous due to such abnormal conditions as partial vaporization of the fuel, priming of the pump, or air in the line connected to inlet 16. These abnormal conditions are usually associated with motordriven vehicles such as automobiles, trucks, and motorcycles. When this longer stroke or overstroking of bellows 12 occurs, the bellows is foreshortened from its free length sufficiently so that the pairs of ribs 58 and 60 associated with bends 50 and 52 are urged into abutment. The abutment of pairs of ribs 58 and 60 transmits a portion of the compression force acting on bellows 12 directly to interconnecting wall portions 54 which decreases the maximum stress to which bends 50 and 52 would otherwise be subjected. This is believed to result in a substantially longer useful service life of bellows 12 compared to prior art pump bellows. Regardless of the theoretical explanation, it has been found that pump bellows 12 does have a substantially longer life than prior art pump bellows of a similar size.

Such bellows 12 were made of polyurethane with an upper mounting ring outside diameter of 1.125 inches, a lower mounting ring outside diameter of 0.437 inch, and a free length of 1.09 inches. Corrugated wall 46 has a free length of 0.82 inch with the outer bends having an outside diameter of 0.81 inch and the inner bends having an inside diameter of 0.37 inch. Each pair of adjacent interconnecting wall portions forms an included angle of approximately 58 and the grooves associated with the bends have an included angle of approximately 20. The apex of the grooves has a radius of approximately 0.006 inch and the pairs of ribs begin approximately 0.037 inch from the apex of their grooves and have a radius of approximately 0.032 inch. The thickness of the outer and inner bends of the corrugated wall is approximately 0.056 inch and the minimum thickness of the interconnecting wall portions immediately adjacent the apex of the grooves associated with the bends is 0.030 inch. The maximum thickness of the interconnecting wall portions is approximately 0.045 inch. This bellows is shown in section one and one half times its actual size in FIG. 2 except for the thickness and detailed shape of the corrugated wall which is shown in section seven and one half times its actual size in FIG. 4.-

The configuration of corrugated side wall 46 with a greater thickness at bends 50 and 52 than the maximum thickness of interconnecting portions 54 and with a lesser wall thickness immediately adjacent the bends than the maximum thickness of the interconnecting wall portions provides a bellows which requires substantially less force to foreshorten and extend than prior art pump bellows. This configuration reduces the actuating force while still preventing the bellows from ballooning or substantially expanding radially when foreshortened to pressurize liquid therein. This substantial reduction in the amount of the force required to actuate bellows 12 increases the efficiency of pump and the service life of bellows 12. This configuration of the corrugated sidewall of bellows 12 also allows the bellows to function satisfactorily in an environment having a substantially lower atmospheric temperature without impairing the service life of the bellows. Compared to prior art pump bellows, this sidewall configuration provides thicker wall portions particularly at the bends 50 and 52 and the maximum thickness of interconnecting wall portions 54, while still requiring less actuating force, which facilitates moulding the bellows without voids, thin spots, and other defects in the corrugated wall which decreases the cost of manufacture of the bellows.

lclaim:

l. A one-piece homogeneously integral bellows of a resilient nonmetallic rubber-like synthetic material for use in a pump having a flexible corrugated generally circular wall with a plurality of interleaved radially and axially spaced outer and inner circumferential bends with interconnecting wall portions, said bends having a greater thickness in cross section than the maximum thickness in cross section of said interconnecting wall portions with said interconnecting wall portions having a lesser thickness in cross section immediately adjacent said bends than said maximum thickness in cross sec tion of said interconnecting wall portions.

2. The one-piece bellows of claim 1 in which said inner bends have an associated pair of circumferential ribs in opposed relation on the outer surface of the interconnecting wall portions.

3. The one-piece bellows of claim 1 in which said outer bends have an associated pair of circumferential ribs in opposed relation on the inner surface of the interconnecting wall portions. I

. The one-piece bellows of claim 3 In which said inner bends have an associated pair of circumferential ribs in opposed relation on the outer surface of the interconnecting wall portions.

5. The one-piece bellows of claim 4 in which said pairs of ribs are adapted to abut when said bellows is foreshortened by overstroking of said bellows by the fuel pump.

6. In a fuel pump of the type having a pumping chamber with an inlet and an outlet, a solenoid actuator with a stroke of variable length for reciprocating one end of a bellows, and a switch means for effecting reciprocation of one end of the bellows by the solenoid actuator, a one-piece bellows fixed at one end, coupled to said pumping chamber, and operably connected at the other end to said solenoid actuator for reciprocation comprising a one-piece homogeneously integral corrugated wall of a flexible resilient nonmetallic rubber-like synthetic material with a plurality of interleaved radially and axially spaced outer and inner circumferential bends with interconnecting wall portions, said bends having a greater thickness in cross section than the maximum thickness in cross section of said interconnecting wall portions with said interconnecting wall portions having a lesser thickness in cross section immediately adjacent said bends than said maximum thickness in cross section of said interconnecting wall portions.

7. The one-piece bellows of claim 6 in which said outer bends have an associated pair of circumferential ribs in opposed relation on the inner surface of the interconnecting wall portions.

8. The one-piece bellows of claim 7 in which said inner bends have an associated pair of circumferential ribs in opposed relation on the outer surface of the interconnecting wall portions.

9. The one-piece bellows of claim 8 in which said pairs of ribs are adapted to abut when said bellows is foreshortened by overstroking of said bellows by the fuel pump. 

1. A one-piece homogeneously integral bellows of a resilient nonmetallic rubber-like synthetic material for use in a pump having a flexible corrugated generally circular wall with a plurality of interleaved radially and axially spaced outer and inner circumferential bends with interconnecting wall portions, said bends having a greater thickness in cross section than the maximum thickness in cross section of said interconnecting wall portions with said interconnecting wall portions having a lesser thickness in cross section immediately adjacent said bends than said maximum thickness in cross section of said interconnecting wall portions.
 1. A one-piece homogeneously integral bellows of a resilient nonmetallic rubber-like synthetic material for use in a pump having a flexible corrugated generally circular wall with a plurality of interleaved radially and axially spaced outer and inner circumferential bends with interconnecting wall portions, said bends having a greater thickness in cross section than the maximum thickness in cross section of said interconnecting wall portions with said interconnecting wall portions having a lesser thickness in cross section immediately adjacent said bends than said maximum thickness in cross section of said interconnecting wall portions.
 2. The one-piece bellows of claim 1 in which said inner bends have an associated pair of circumferential ribs in opposed relation on the outer surface of the interconnecting wall portions.
 3. The one-piece bellows of claim 1 in which said outer bends have an associated pair of circumferential ribs in opposed relation on the inner surface of the interconnecting wall portions.
 4. The one-piece bellows of claim 3 in which said inner bends have an associated pair of circumferential ribs in opposed relation on the outer surface of the interconnecting wall portions.
 5. The one-piece belLows of claim 4 in which said pairs of ribs are adapted to abut when said bellows is foreshortened by overstroking of said bellows by the fuel pump.
 6. In a fuel pump of the type having a pumping chamber with an inlet and an outlet, a solenoid actuator with a stroke of variable length for reciprocating one end of a bellows, and a switch means for effecting reciprocation of one end of the bellows by the solenoid actuator, a one-piece bellows fixed at one end, coupled to said pumping chamber, and operably connected at the other end to said solenoid actuator for reciprocation comprising a one-piece homogeneously integral corrugated wall of a flexible resilient nonmetallic rubber-like synthetic material with a plurality of interleaved radially and axially spaced outer and inner circumferential bends with interconnecting wall portions, said bends having a greater thickness in cross section than the maximum thickness in cross section of said interconnecting wall portions with said interconnecting wall portions having a lesser thickness in cross section immediately adjacent said bends than said maximum thickness in cross section of said interconnecting wall portions.
 7. The one-piece bellows of claim 6 in which said outer bends have an associated pair of circumferential ribs in opposed relation on the inner surface of the interconnecting wall portions.
 8. The one-piece bellows of claim 7 in which said inner bends have an associated pair of circumferential ribs in opposed relation on the outer surface of the interconnecting wall portions. 